Telephone-exchange system



Jan. 1 1924 J. L. M QUARRIE ET AL TELEPHONE EXCHANGE SYSTEM Filed Dec. 4,1919

m 5 M :F dd n 6 WM. m/ MM 6 Ra m EE (aw Patented Jan. 1, 1924.

JAMES L.

MCQUARRIE AND CHARLES L. GOODRUM, OF NEW YORK, N. Y., ASSIGNORS T0 WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A COR- PORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed December 4, 1919. Serial No. 342,329.

To} all whom it may concern:

Be it known that we, J AMES L. MGQUAR- RIE and CHARLES L. GOODRUM, citizens of the United States, both residing at New York, in the county of New York and State of New York, have invented new and useful Improvements in Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to improvements in telephone systems and has particular reference to a line switch employed in machine switching.

Switches of known construction such as the Keith line switch are provided, in addition to other apparatus, with line and cutoff relays individual to each of the subscribers lines served by the switch. In addition to other functions, each cut-off relay operates, when the line to which it is individual is called and the substation line circuit is closed upon response of the subscriber, to prevent the line switch serving said line from operating to extend the line to an idle trunk.

An object of the present invention is to provide a switch wherein the number of relays employed is materially reduced by dividing the subscribers lines into groups each of which is served by a mechanism common to all of the lines therein.

Another object is to avoid the use of cutoff relays for preventing the extension of subscribers lines to idle trunks when the r subscribers respond to calls made to their lines.

A preferred embodiment of the invention is illustrated in the accompanying drawing wherein Fig. 1 is a diagrammatic illustration of the circuit arrangement employed in carrying out the invention, Fig. 2 is a frag mentary perspective view of the switch structure, Fig. 3 is a similar detail view of a set of line terminals and the associated plunger.

Referring to the drawing and more particularly to Figs. 2 and 3, the line switch is shown as consisting of a shaft 4, rotatably mounted in a frame 5 and carrying a pinrality of plungers 6, each of which is individual to one of the subscribers lines served by the switch. Each plunger has associated therewith a magnet 7 as is usual in this type of switch, the armature of the magnet, when the same is energized, being designed to disengage its associated plunger from the frame 5 and engage the same with the spring contacts 8 and 9 individual to a particular line. The contacts 8 and 9 are normally in engagement with terminals 10 to permit of the energization of a line relay when a call is initiated at a particular substation. In the course of the operation of the switch, the associated plunger 6 is operated to engage contacts 8 and 9 to open the circuit for said line relay and simultaneously extend the calling line through terminals 11 to an idletrunk. As is usual in switches of this type, the selection of an idle trunk causes the energization of a master magnet 12, which operates the shaft of the switch to position the remaining plungers mounted thereon in alignment with the terminals of the next idle trunk.

In the operation of switches having general characteristics as described above,there is usually provided a line and a cut-off relay individual to each line, a function of the cut-off relay being to prevent the extension of the subscribers line to an idle trunk when said line is called. It is proposed, in the present invention to dispense with the use of the cut-off relays for this purpose. To this end the switch is provided with a magnet 13 which, if any one of the lines served by the switch is called, will be energized and in so doing will move the frame 5 about the shaft 4 as a pivot against the tension of the spring 14. This movement of the frame 5 will give the plungers in engagement therewith a slight rotary movement which will position the same out of alignment with or in offset relation to the line terminals in the bank of the switch. This movement, however, is not sufiicient to prevent engagement of a plunger 6 with its associated contact springs 8 and 9 when the plunger is operated. Each contact spring 9 is provided with a stop or projection 15 arranged in the path of movement of the plunger 6 when in its ofiset position so that when operated the plunger will engage said stop and be limited in its movement. The plunger will however, engage springs 8 and 9 and cause the same to operate sufliciently to open the terminals 10, but not suiiiciently to engage the terminals 11. This operation will open the circuit of the line relay and,

at the same time prevent the extension of the subscribers line to an idle trunk. At the termination of the operation, magnet 13 is deenergized to permit the frame 5 to return to its normal position where the plungers in engagement therewith will again be set properly so that any one of them may be caused to engage the terminals of a calling line.

In carrying out the invention, the subscribers lines served by the switch are preferably arranged in groups, two of which are indicated in Fig. 1 by A and B. Each group of lines has a common line relay 16, and a cut-off relay 17 which is slow to release. A plurality of auxiliary line relays 18, 18 and 18" corresponding in num ber to the number of lines in a group are also provided. Each auxiliary line relay is common to a plurality of lines, each of which is located in a different one of the groups of lines. Thus the relay 18, is common to the first line appearing in each of the several groups A, B, etc., the relay 18 to the second line in each of the groups, and so on.

It is now believed that the invention will be fully understood from the following detailed description of the operation. When a call is initiated at substation 19, a circuit is closed for line relay 16 of group A, extending from grounded battery, left winding of said relay, back contact and armature of relay 17 ,upper terminal 10, contact spring 8, the apparatus at substation 19, the contact spring 9, the lower terminal 10, armature 21 and its back contact and right winding or relay 16 to ground. Relay 16 energizes and establishes a circuit for cut-off relay 17 of group A which energizes. Inasmuch as all the contacts of the line relay are controlled by the relay 17, a second call initiated in the same group will not interfere with the first call. The circuit for line relay 16 is opened by the energization of relay 17 through the armatures 20 and 21 of relay 17 and relay 16 releases to open the circuit for relay 17. Before relay 17 can release a circuit is established for the auxiliary line relay 18 common to the first lines appearing in each group, which circuit is traceable from grounded battery, left winding of relay 18, armature 20 and its front contact, from thence over the previously described energizing circuit for relay 16, armature 21 and its front contact and right winding of relay 18 to ground. Relay 18 energizes and closes a circuit for magnet 7 individual to substation 19, which circuit extends from grounded battery, winding of said magnet, front contact and lowermost armature of relay 17 and front contact and armature of relay 18 to ground. Magnet 7 energizes and operates its associated plunger 6 to engagesprlng contacts 8 and 9. In the normal operation of plunger 6, contacts 8 and 9 operate to disengage terminals 10 and engage the terminals of the idle preselected trunk 22. This is accomplished before relay 17 can release to open the circuit for relay 18 at which time relays 16, 17 and 18 will again be ready for use. The operation of contacts 8 and 9 closes a circuit for the magnet 12 of the master allotter extending from grounded battery, winding of saidmagnet, wiper 24, a terminal of the selected trunk and contact to ground. Magnet 12 oper ates wiper 24 to pass over terminals of trunks until the next idle trunk is found. During this operation, shaft 4 of the switch rotates and carries with it the plungers 6 in order to position the same before the terminals of the idle trunk. The calling line is now extended to the next succeeding, switch and the subscriber at substation 19 may operate his dial in the usual manner. The extension of the calling line to the next switch places a ground upon the conductor 23 which maintains magnet 7 energized throughout the duration of the call, said ground also extending to the test terminal of line 19 to indicate the busy condition thereon. At the termination of the call this ground is removed and magnet 7 deenergizes to permit plunger 6 to return to its normal position.

When the substation 19 is called, a connector switch is engaged with the terminals of the line in any manner well known in the art and if the line is idle a circuit is immediately established for magnet 13. This circuit extends from grounded battery through the winding of magnet 13, the conductor 26, the brush of the connector switch, wiper 31 in position 2 which is the test position, and the armature and contact of relay 32 to ground. Magnet 13 is energized in this circuit to rotate the frame 5 of the switch and thus move the plungers 6 out of direct alignment with the terminals of the bank. The relay 32 of the connector switch is the equivalent of the second slow relay 11 shown in Fig. 1 of the U. S. application of Clausen and Goodrum filed July 16, 1918, Serial No. 245,145, which relay releases upon the termination of the last series of impulses transmitted to the con neetor. lVhen, upon test, a line is found to be idle the side switch wipers of the connector are moved to position 3 in which position the side switch wiper 33 connects ground to brush 3 1-. A circuit is then es tablished for the magnet 7 individual to the line 19 over the test conductor 23, brush 3st and the wiper 33 to ground. Owing to the construction of wiper 31 which bridges adjacent contacts, the circuit for magnet 13 is maintained until the magnet 7 is energized.

Upon energization of magnet 7, its asso ciated plunger is engaged with contacts 8 and 9 and the stop 15 carried by the latter with the result previously described. Magnet 13, being energized only momentarily, will release as soon as magnet 7 is energized and frame 5 together with the remaining plungers' 6 will restore to normal under the action of spring 14:. At the termination of the call, ground is removed from conductor 23 in the usual manner and magnet 7 deenergizes to permit plunger 6 to restore to normal.

IVhat is claimed is:

1. In atelephone system, a subscribers line, a trunk, a switch for connecting said line to said trunk, operating means for said switch normally connected to said line, a single member operable when a call is initiated on said line for disconnecting the line from said operating means, and for extending said line to said trunk, and means for controlling said member to effect the disconnection of the said line and operating means only, when said line is called.

2. In a telephone system, a group of subscribers lines, a trunk, a line relay common to said group of lines and normally connected thereto, a switch, means at said switch for disconnecting said relay from a calling line and extending said line to said trunk, and means for controlling the last named means to effect only the disconnection of said relay from said line when the line is called.

3. In a telephone system, a plurality of lines, a trunk to which said lines may be extended, a switch, a relay at said switch common to said lines, and responsive to the initiation of a call on any one. of them, a second relay, means responsive to the energization of the first named relay energizing said second relay, and means individual to a calling line actuated by the energization of said second relay for extending said line to said trunk.

4. In a telephone system, roups of subscribers lines, a. trunk, a switch, means common to each group of lines responsive to the initiation of a call on a line in the asso ciated group, other means common to a plurality of lines located in different groups, and individual means for each line responsive to the operation of said other means for extending said line to one of said trunks.

5. In a telephone system, groups of sub scribers lines, a plurality of trunks, a switch, means at said switch for preselecting an idle one of said trunks, means common to each group of lines responsive to the initiation of a call on a line in the associated group, other means common to a plurality of lines located in different groups, and individual means for each line responsive to the operation of said other means for extending said line to said idle trunk.

6. In a telephone system, a subscribers line, a trunk, a switch, means normally connected to said line for operating said switch, a plunger for said switch operable when a call is initiated on said line for disconnecting the line from said operating means and for extending said line to said trunk, and means operable when said line. is called for causing said plunger to disconnect said line and operating means only.

7. In a telephone system, a subscribers line, a trunk, a switch, means normally connected to said line for operating said switch, a plunger for said switch normally in alignment with the terminals of said line, a magnet for operating said plunger when a call is initated on said line for disconnecting said line from said operating means and for extending said line to said trunk, means operable when said line is called for offsetting said plunger with respect to the terminals of said line but permitting engagement thereof, and means for controlling the operation of said plunger whereby said terminals are disconnected from said operating means only.

8. In a telephone system, a subscribers line, a trunk, a switch, means normally connected to said line for operating said switch, a plunger for said switch normally in alignment with the terminals of said line, a mag net for operating said plunger when a call is initiated on said line for disconnecting said line from said operating means and for extending said line to said trunk, means operable when said line is called for olfsetting said plunger with respect to the terminals of said line but permitting en-- gagement thereof, and a stop associated with one of said terminals for limiting the movement of said plunger when operated whereby said terminals are disconnected from said operating means only.

In witness whereof, we have hereunto subscribed our names this last day of December, A. D., 1919.

J AMES L. McQUAR-RIE, CHARLES L. GOODRUM. 

